A pentraxin was isolated from acute phase goat serum by its calcium-dependent affinity for agarose, and although it did not bind to phosphorylcholine immobilised on Sepharose, its binding to agarose was reversed by exposure to fluid phase phosphorylcholine. It was identified as goat C-reactive protein on the basis of its immunochemical cross-reactivity with human and bovine C-reactive protein. The molecule was composed of five identical, glycosylated, non-covalently associated subunits, each of molecular weight approx. 24000. Acute phase serum levels in a small number of samples were not significantly different from normal levels (means 72 and 55 μg/ml, respectively), suggesting that goat C-reactive protein is not a major acute phase reactant. No other pentraxin was detected in goat serum.

Conference Abstract| February 01 1982 Lipoprotein Binding by Aggregated C-Reactive Protein FC De Beer; FC De Beer 1Immunological Medicine Unit Search for other works by this author on: This Site PubMed Google Scholar Anne K Soutar; Anne K Soutar *Dept of Medicine, MRC Lipid Metabolism Unit Search for other works by this author on: This Site PubMed Google Scholar Iris Trainer; Iris Trainer **Dept of Chemical Pathology, Royal Postgraduate Search for other works by this author on: This Site PubMed Google Scholar A Feinstein; A Feinstein ***Medical School, London W12 OHS and ARC Babraham Search for other works by this author on: This Site PubMed Google Scholar MB Pepys MB Pepys 1Immunological Medicine Unit Search for other works by this author on: This Site PubMed Google Scholar Clin Sci (Lond) (1982) 62 (2): 9P–10P. https://doi.org/10.1042/cs062009Pb Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Cite Icon Cite Get Permissions Citation FC De Beer, Anne K Soutar, Iris Trainer, A Feinstein, MB Pepys; Lipoprotein Binding by Aggregated C-Reactive Protein. Clin Sci (Lond) 1 February 1982; 62 (2): 9P–10P. doi: https://doi.org/10.1042/cs062009Pb Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1982 The Biochemical Society and the Medical Research Society1982 Article PDF first page preview Close Modal You do not currently have access to this content.

A test is described which is capable of differentiating and measuring by titration the individual classes of antibody reacting with a bacterial suspension. The serum or fluid under test is incubated with the bacteria which are then very well washed and added to indicator red cells linked with specific antiglobulin reagents. Sensitization of the bacteria by a particular class of antibody is shown by haemagglutination (passive) of the appropriate red cells. Agglutination of the bacteria themselves does not preclude an analysis. The reaction, which has been developed on a brucella system, has been designated Mixed Reverse Passive Antiglobulin Haemagglutination (or MRPAH for short).

THE antigen receptor on the plasma membrane of both human and murine bone marrow-derived (B) lymphocytes has been shown to be mainly monomeric IgM (refs 1–5), but the mechanism of attachment of this IgM is not known. Studies on other membrane proteins (for example, glycophorin6, cytochrome b5, (ref. 7) and probably HLA8) have shown that they are bound to the membrane by means of a hydrophobic polypeptide stretch in the C-terminal region, but secreted IgM heavy chains terminate in an extra-domain sequence of 19 amino acid residues9–11, which is not sufficiently hydrophobic to act as an integral membrane component. Membrane μ chains, however, might carry a further hydrophobic C-terminal polypeptide section instead of, or in addition to, the C-terminal stretch present in secreted μ chains. To investigate this possibility, we have exploited the fact that a tyrosine residue forms the C terminus of all examined secreted μ chains, including those of human and mouse. Since it is improbable that a hydrophobic extension on the membrane μ chain would coincidentally carry a C-terminal tyrosine residue, we have examined the surface IgM from a murine B lymphocytoma, McPc 1748 (ref. 12), and a human lymphocytic B-cell line, Bristol-8 (Bri-8, obtained from G. D. Searle, High Wycombe), which also carries surface IgM (F. Kramer, personal communication), to see whether a C-terminal tyrosine residue can be cleaved from their purified μ chains by treatment with carboxypeptidase. Our data show that it can, indicating that membrane-bound IgM lacks an extra hydrophobic piece.

THE molecules of different classes of immunoglobulin are built from units of similar structure, containing two light and two heavy polypeptide chains linked through disulphide bridges1. The IgG molecule, which contains one such unit of molecular weight 150,000, has been shown by electron microscopy to be a flexible Y-shaped molecule2,3 with two arms corresponding to the Fab regions carrying the two antigen-binding sites4 and a third (Fc) arm. The IgM molecule consists of five Y-shaped units, each with a molecular weight of 180,000, linked cyclically by disulphide bridges through the Fc arms5–8. IgA commonly occurs in the form of a bridged dimer. Such an IgA dimer preparation has been examined in the electron microscope, but the molecules shown and described had no distinct Fc feature9. We have examined two preparations of dimeric IgA, one isolated from the serum of mice carrying plasmacytoma MOPC 315, and the other from the serum of a patient (W.E.) with multiple myelomatosis. 10 to 15 ml. of each serum was pumped through a column (2.5 × 100 cm) of ‘Sephadex G-200’ (Pharmacia). Fractions were selected from the trailing side of the breakthrough peak, pooled on the basis of their antigenic purity, and concentrated by ultrafiltration (Amicon). Each preparation sedimented in the analytical ultracentrifuge as a single component with a sedimentation coefficient (S20,w) of about 9.5S and after treatment with 5 mM dithiothreitol dissociated to the monomer of 6.3S.

THE two major classes of antibody molecule, IgG and IgM1, have molecular weights of 150,000 and 900,000, respectively. They are composed of heavy and light polypeptide chains. In IgM each heavy (μ) chain, molecular weight 70,000, is linked by a disulphide bridge to a light (L) chain, molecular weight 23,000, and is probably linked by three further bridges to other μ chains2–10.